In a projector that uses light of a plurality of colors to project a color image, the quantity of light of each color must be adjusted according to the human luminosity factor with respect to the light of each color and the optical output capability of the light sources that emit the light of each color to project an image with superior white balance. Problems therefore arise regarding both the inability to adequately exhibit the optical output capability for each color and the reduced brightness of white images.
For example, in the case of a projector that uses as a light source a plurality of LEDs that emit each of red light, green light, and blue light, according to the current state of the art, the performance of a green LED that emits green light is lowest and the performance of a blue LED that emits blue light is highest. As a result, the luminance of a blue LED must be eliminated in order to project an image of superior white balance.
Patent Document 1 discloses a projection-type display device that is provided with a supplemental green LED apart from the green LED that is used as the green light source that mixes green light with blue light. By using an LED array in which a supplemental green LED is aligned with a blue LED as the blue light source in this projection-type display device, green light is mixed with blue light. The quantity of green light can thus be increased, whereby an image can be projected with brighter white light and superior white balance without eliminating the luminance of the blue LED.